PSD analysis was carried out to measure the size distribution
of the DHSA crystals as per the published procedure (Abidin et al.,
2009) using a Malvern Instruments Mastersizer 2000 and Hydro
2000S particle size analyzer. The equipment was set to process
particle sizes from 0.020 to 2000.000 m. The Mie-Scattering analysis
model was used for diffraction pattern measurements. The reflective index of DHSA was 1.520 while for water, which was used
as the dispersant, it was 1.330. The Mastersizer was set to record
background measurements for 20 s followed by sample measurements
for 20 s. DHSA crystals were then inserted into a designated
vessel where they were introduced into the dispersion module until
an obscuration level of 10.0–20.0 was achieved. Three measurements
were obtained for each sample and the average value was
taken as the final result. The specific surface area and surface- and
volume-weighted mean diameters of the crystals were determined
along with d(0.1)-, d(0.5)- and d(0.9)-cumulative undersizes.